Refer to your device page to find a link to the latest images (Last images part of the table).

Download the images and the md5 checksum

Download fastboot from the latest images tools directory (it is a prebuilt x86 binary for GNU/Linux). Note that you can still use this binary on a system with different hardware architecture as long as you have 32-bit version of needed libraries installed. It is known to work with 32-bit version of GNU C Library and legacy GNU Standard C++ Library version 3 installed.

Make sure fastboot is executable:

chmod a+x fastboot

System permissions are needed to access the device with fastboot. You will see it stops on '<waiting for device>' message when you are missing permissions while flashing. Unless you are going to use root account for running fastboot you will need to setup udev rules and add your user to plugdev group.